CN114244291B

CN114244291B - Power driving amplifying circuit and method

Info

Publication number: CN114244291B
Application number: CN202111551848.XA
Authority: CN
Inventors: 杨少军; 高东兴
Original assignee: Shenzhen Jingyang Electronics Co ltd
Current assignee: Shenzhen Jingyang Electronics Co ltd
Priority date: 2021-12-17
Filing date: 2021-12-17
Publication date: 2022-09-06
Anticipated expiration: 2041-12-17
Also published as: CN114244291A

Abstract

The invention provides a power driving amplification circuit and a method, which are applied to class B or class AB power driving amplification. The method comprises the following steps: applying voltage feedback control to a pull-down driving power tube and applying current feedback control to a pull-up driving power tube; controlling the pull-up driving power tube connected with one path of the push-pull output by a voltage feedback control loop to enable the output voltage of the circuit to meet the preset working requirement; controlling the pull-down driving power tube connected with the other push-pull output path by a current feedback control loop; and detecting the pull-up current, comparing the pull-up current with a current reference value, selecting a larger or smaller current, and inputting the larger or smaller current into a current feedback control loop to realize current feedback control on the pull-down driving power tube. The matching performance of the pull-up drive and the pull-down drive is better, the overall stability is higher, the harmonic distortion is extremely low, and the production cost is lower.

Description

Power driving amplifying circuit and method

Technical Field

The invention relates to the field of push-pull type class B/class AB power amplification circuits, in particular to a push-pull type class B/class AB power driving amplification circuit and a driving method thereof.

Background

In a general push-pull type B or class AB power amplifier, different types of power amplifier tubes are used in pull-down driving and pull-up driving of signals. For example, in an emitter-follower push-pull amplifier, a PNP transistor or a P-type fet is generally used as a pull-down driver; in the pull-up driving, an NPN type triode or an N type field effect transistor is used. The pull-up and pull-down driving tubes of the drain-driven push-pull amplifier are also of different types.

In the prior art, the circuit amplification structure is very symmetrical, the implementation scheme is simple, and the cross-over distortion can be well adjusted and optimized only by adjusting the bias working point in the design.

However, the existing push-pull type class b or class ab power amplifier circuit must use different types of power tubes in pairs for operation, and the mobility of hole carriers and electron carriers in semiconductors are greatly different, so that the P-type driving tube and the N-type driving tube cannot be precisely matched essentially. More importantly, the power tube with holes as main carriers has limited driving capability due to low mobility. For example, in a typical semiconductor process, the on resistance of a pfet is 3 to 4 times that of an nfet. In order to match the output impedance of the pull-up drive and the pull-down drive, the area and the input capacitance of the P-type field effect transistor are 3 to 4 times of those of the N-type field effect transistor. The area and cost of the P-type fet dominate.

In addition, when the temperature and voltage change and the doping concentration in the semiconductor production process change, due to different change characteristics of hole and electron carriers, the mismatch of the pull-up driving tube and the pull-down driving tube is increased, and thus the harmonic distortion of the power amplification circuit is increased sharply.

In the push-pull amplifying circuit adopting different types of driving transistors such as a triode or an IGBT, similar problems exist due to the fact that the types of main carriers of a pull-up driving tube and a pull-down driving tube are different.

In the prior art, the currently superior gauge driving methods mainly include two methods: first, as in The scheme described in "Integrated Audio Amplifiers in BCD technology" (The spring International Series in Engineering and Computer Science, vol 418.spring, Boston, MA.), a method of driving a full N-tube DMOS driving stage by using a phase division and current mirror method is adopted, but The method requires that a signal is divided into an upper half period and a lower half period first, and then a proportional current amplification method is adopted to control an output driving tube. Secondly, as described in the section A/B flowing buffer BiCMOS power op-amp (IEEE j ournal of solid-state circuits30.6(1995):670-676.Lish, C. Andrew), a floating up-down voltage feedback driving method is adopted for driving, and because the up-down power driving tube adopts a voltage feedback loop, the static working point of the up-down power driving tube is difficult to control.

Disclosure of Invention

Aiming at the defects of the prior art. Specifically, the invention provides the following technical scheme:

in one aspect, the invention provides a power driving amplifying circuit, wherein the circuit is a single-ended driving circuit;

the power driving amplification circuit comprises a voltage amplification circuit, a current detection circuit, a current selector and a current control loop; the emitter following amplifying circuit is connected with a current detecting circuit, the current detecting circuit is connected with a current selector, and the current selector sends the selected current into a current control loop for controlling the output current;

the emitter following amplifying circuit consists of an inverse input operational amplifying circuit and a power tube NH1 connected with the output end of the inverse input operational amplifying circuit;

the current detection circuit is composed of an operational amplifier OP2, a power tube NH2 and a transistor PH1, so that the current of the power tube NH1 and the current of the power tube NH2 are reduced in equal proportion; wherein, the power tube NH2 is connected with the inverting input end of the operational amplifier OP2, and the transistor PH1 is connected with the output end of the operational amplifier OP 2; the current detection circuit outputs current to be connected with the current selector;

the current selector selects the smaller current of the reference current Iref1 and the output current of the current detection circuit and sends the smaller current to the current control loop;

the current control loop forms a current control negative feedback circuit through an operational amplifier OP3 and a power tube NL1 connected with the output end of the operational amplifier OP3 based on the output current of the current selector and the working current Iref2, and controls the working state of the power tube NL 1.

Preferably, the power tube NH1 is a pull-up driving tube, and the power tube NL1 is a pull-down driving tube;

the source of the power tube NH1 and the drain of the power tube NL1 are both connected to the output pin of the power driving amplifier circuit.

Preferably, the inverting input operational amplifier circuit is composed of an operational amplifier OP1, a feedback resistor Rf, and an input resistor Rin;

the input resistor Rin is connected with the inverting input end of an operational amplifier OP1, and the output end of the operational amplifier OP1 is connected with the grid electrode of a power tube NH 1; the feedback resistor Rf is connected with the inverting input end of the operational amplifier OP1 and the source electrode of the power tube NH 1;

the output end of the operational amplifier OP1 is connected with the grid of the power tube NH 2.

Preferably, the non-inverting input terminal of the operational amplifier OP2 is connected to the source of the power transistor NH1 and the output pin of the power driving amplification circuit;

the inverting input end of the operational amplifier OP2 is connected with the source electrode of the power tube NH2 and the drain electrode of the transistor PH 1.

Preferably, an inverting input terminal of the operational amplifier OP3 is connected to the output current terminal Imin selected by the current selector and the drain of the power tube NL 2; the non-inverting input end of the operational amplifier OP3 is connected with a working current Iref 2;

the gate of the power tube NL2 is connected to the output end of the operational amplifier OP 3.

Preferably, the same carrier type is used for the power tube NH1 and the power tube NL 1.

In another aspect, the present invention further provides a power-driven amplification method, which can be implemented by the power-driven amplification circuit described above, and can be applied to class b or class ab power-driven amplification, where the method includes:

applying voltage feedback control to the pull-up driving power tube and applying current feedback control to the pull-down driving power tube;

controlling the pull-up driving power tube connected with one path of the push-pull output by a voltage feedback control loop to enable the output voltage of the circuit to meet the preset working requirement;

controlling the pull-down driving power tube connected with the other push-pull output path by a current feedback control loop;

detecting a pull-up current, comparing the pull-up current with a working current reference value, selecting a larger or smaller current, and inputting the larger or smaller current into a current feedback control loop to realize current feedback control on a pull-down driving power tube;

the pull-up driving power tube and the pull-down driving power tube adopt the same carrier type.

Preferably, in the power driving amplification method, voltage feedback control is applied to the pull-down driving power tube, and current feedback control is applied to the pull-up driving power tube; controlling the pull-down driving power tube connected with one path of the push-pull output by a voltage feedback control loop to enable the output voltage of the circuit to meet the preset working requirement; controlling the pull-up driving power tube connected with the other path of the push-pull output by a current feedback control loop; detecting the pull-down current, comparing the pull-down current with a working current reference value, selecting a larger or smaller current, and inputting the larger or smaller current into a current feedback control loop to realize current feedback control of the pull-up driving power tube;

In addition, the invention also provides a power driving amplifying circuit, wherein the power driving amplifying circuit is in differential driving;

the power driving amplification circuit comprises a differential driving circuit I, a differential driving circuit II and a current selector;

the first differential drive circuit is composed of a first emitter following amplification circuit, a first current detection circuit and a first current control circuit; the first emitter follower amplifying circuit is connected with the first current detection circuit, and the first current detection circuit is connected with the current selector; the current selector is used for controlling the common-mode current of the pull-down driving tube in the first current control loop;

the differential driving circuit II is composed of an emitter following amplifying circuit II, a current detection circuit II and a current control circuit II; the second emitter following amplifying circuit is connected with a second current detection circuit, and the second current detection circuit is connected with a current selector; the current selector is used for controlling the common-mode current of the pull-down driving tube in the current control loop II by using the selected current;

the first emitter following amplifying circuit is used for driving an OUTP (output terminal) pin of the differential output, and the second emitter following amplifying circuit is used for driving an OUTN (output terminal) pin of the differential output;

the first current detection circuit is composed of an operational amplifier OP2P, a power tube NH2, a transistor PH1 and a transistor PH2 and is used for detecting the current of the differential positive terminal; the output voltage of the operational amplifier OP2P is the same as the OUTP pin; output currents Iph1 and Iph2 of the first current detection circuit are used for a first current control loop driven by differential positive end pull-down;

the second current detection circuit is composed of an operational amplifier OP2N, a power tube NH4, a transistor PH3 and a transistor PH4 and is used for detecting the current of the differential negative terminal; the output voltage of the operational amplifier OP2N is the same as the OUTN pin; output currents Inh1 and Inh2 of the current detection circuit II are used for a current control circuit II driven by the differential negative terminal pull-down;

the first current control loop obtains an input current Ip1 of the first current detection circuit based on the output current of the first current detection circuit, the output current of the current selector and the reference current Iref, and controls the output current of the power tube NL1 used for pull-down driving to be consistent with a target current based on the input current Ip 1;

the second current control loop obtains an input current In1 of the second current control loop based on the output current of the second current detection circuit, the output current of the current selector and the reference current Iref, and controls the output current of the power tube NL4 for pull-down driving to be consistent with the target current based on the input current In 1.

Preferably, the first current control loop is composed of operational amplifiers OP3P, NL1, NL 2;

the inverting input end of the operational amplifier OP3P is connected with a pin OUTP and the drain electrode of a power tube NL 1; the non-inverting input end of the operational amplifier OP3P is connected with an input current Ip 1;

the grid electrode of the power tube NL2 and the grid electrode of the power tube NL1 are respectively connected with the output end of the operational amplifier OP3P, and the drain electrode of the power tube NL2 is connected with an input current Ip 1;

the second current control loop is composed of operational amplifiers OP3N, NL3 and NL 4;

the inverting input end of the operational amplifier OP3N is connected with a pin OUTN and the drain of a power tube NL 3; the non-inverting input end of the operational amplifier OP3N is connected with an input current In 1;

the gate of the power tube NL3 and the gate of the power tube NL4 are respectively connected to the output end of the operational amplifier OP3N, and the drain of the power tube NL4 is connected to the input current In 1.

Preferably, the power driving amplification circuit includes: a power tube NH1 and a power tube NH4 which are used as pull-up driving tubes, wherein the power tube NH1 is used for driving the upper half cycle of an OUTP signal, and the power tube NH4 is used for driving the upper half cycle of an OUTN signal;

the power tubes NH2 and NH3 are small-scale images of the power tube NH1 and are used for detecting the output current of the power tube NH1, and the power tubes NH5 and NH6 are small-scale images of the power tube NH4 and are used for detecting the output current of the power tube NH 4.

Preferably, the power driving amplification circuit includes: a power tube NL1 and a power tube NL4 as pull-down driving tubes, the power tube NL1 driving the second half cycle of the OUTP signal, and the power tube NL4 driving the second half cycle of the OUTN signal;

power tube NL2 and power tube NH3 are small-scale mirrors of power tube NL1, which are used for reference comparison in a pull-down drive current control loop.

Preferably, the operational amplifiers OP1P/OP1N, OP2P/OP2N, OP3P/OP3N are respectively used for loop control; the input resistor Rinp/Rinn and the feedback resistor Rfp/Rfn are used for adjusting the voltage gain of the power amplifying circuit; the current selector outputs the selected control current for the current control loop.

Preferably, Ip1 is the sum of the output current Inh2 and the reference current Iref, minus the smaller current Imin output after the current selector selects.

Preferably, In1 is the sum of the output current Iph2 and the reference current Iref, minus the smaller current Imin output after the current selector selects.

Preferably, the power tubes NH1, NH4, NL1 and NL4 use the same carrier type.

In addition, the invention also provides a power driving amplification method, which can be applied to the class B or class AB differential output push-pull amplification output driving, and the method comprises the following steps:

applying voltage feedback control based on an active feedback network to a pull-up driving power tube connected with a push-pull output, so that the output voltage meets the voltage requirement; applying current feedback control to a pull-down driving power tube connected with the other path of the push-pull output; detecting a pull-up current, comparing the pull-up current with a working current reference value, selecting a larger or smaller current, and taking the selected output current of the circuit, the working current and the current detection circuit as a control basis of current feedback control on a pull-down driving power tube; or

Applying voltage feedback control based on an active feedback network to a pull-down driving power tube connected with a push-pull output path so that the output voltage meets the voltage requirement; applying current feedback control to a pull-up driving power tube connected with the other path of the push-pull output; detecting a pull-down current, comparing the pull-down current with a working current reference value, selecting a larger or smaller current, and taking the selected circuit, the working current and the output current of the current detection circuit as a control basis of current feedback control on a pull-up driving power tube;

Preferably, the current selector includes: a current comparator CMP, field effect transistors PSW1, PSW2, PSW3, PSW 4;

the current comparator CMP compares the samples of the input current, when the input current at the positive end is larger, the outp of the current comparator CMP outputs a high level, and the outn of the current comparator CMP outputs a low level; when the input current of the positive terminal is small, the outp of the current comparator CMP outputs a low level, and the outn of the current comparator CMP outputs a high level;

the field effect transistors PSW1, PSW2, PSW3, PSW4 are used to switch select outn, outp of the current comparator CMP to control the output of the current selector.

Preferably, the power-driven amplifying circuit is integrated in a circuit chip. In order to facilitate the application of the power-driven amplifier circuit in specific products, the single-ended and differential power-driven amplifier circuits may be integrated into a circuit chip for use, or may be implemented by using conventional circuit module components according to specific use requirements or design requirements, so as to perform integrated packaging, or perform block packaging according to circuit module differentiation (for example, functional differentiation, etc.), or perform matching and combination with other circuit modules used in association to form one or more circuit modules, and perform packaging or perform no packaging.

Preferably, the power driving amplification circuit is applied to audio power amplification.

Preferably, the power tube is any one of a field effect tube, a triode, an LDMOS and an IGBT.

Compared with the prior art, the scheme of the invention adopts the same high-efficiency majority carriers, so that the matching of the pull-up drive and the pull-down drive in the push-pull amplifying circuit is better, and the push-pull amplifying circuit is insensitive to the changes of temperature, voltage, semiconductor process and the like, thereby obtaining higher overall stability. In addition, because the control loop is adopted to control the working point of the power tube, the harmonic distortion of the circuit is extremely small. Finally, since the electron mobility is much higher than that of the hole, the area and cost can be saved by more than 50% when the N/P fet driving in the prior art has the same output capability, compared to the typical full N fet driving. Thus, the design has greater advantages over existing solutions in terms of overall performance and cost.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic diagram of a single-ended driving push-pull power amplifier circuit according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a differentially driven push-pull power amplifier circuit according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating an embodiment of a current selector module according to the present invention;

fig. 4 is a schematic diagram of an implementation method of a class b/class ab power driving circuit according to an embodiment of the present invention;

fig. 5 is a method for implementing the differential output class b/class ab power driving circuit according to the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive effort based on the embodiments of the present invention, are within the scope of the present invention.

Aiming at the defects in the prior art, the invention provides a class B/class AB driving circuit and a driving method thereof. In one particular embodiment, the main ways are as follows:

in the push-pull circuit, the pull-up drive and the pull-down drive both adopt power drive tubes (namely power tubes) with the same majority carriers. Such as NPN-type transistor or N-type fet, etc., it is also possible to use a power driving transistor with holes as the majority carriers, such as PNP-type transistor or P-type fet, or other types of semiconductor process power driving transistors (e.g., LDMOS, IGBT), etc.

The pull-up drive and the pull-down drive respectively use a voltage feedback control loop and a current feedback control loop, so that they stably operate. When an NPN type triode or an N type field effect transistor is adopted, the pull-up drive is stabilized through a voltage feedback control loop; the pull-down drive is stabilized by a current feedback control loop. When a PNP type triode or a P type field effect transistor is adopted, the pull-up drive adopts current feedback loop control, and the pull-down drive adopts a voltage feedback control loop.

The control current of the current feedback control loop is the power tube current in the voltage control loop obtained by detection and collection. And controlling the pull-down driving tube according to the detection current, so that the working current and the working voltage of the whole driving circuit can be stable.

In a more specific example of the current control method, a current selector can be adopted, so that the situation that positive and negative half cycles of a signal need to be divided and respectively driven is avoided, and the whole circuit is simple and efficient.

Example 1

In a specific embodiment, as shown in fig. 1, it is a preferred structure of a single-end driven push-pull power amplifier circuit provided by the present invention. In this embodiment, in order to facilitate the explanation of the idea and the specific scheme of the present invention, the power transistor is exemplified by an N-type field effect transistor. Of course, the power transistor may be a field effect transistor, or may also be any semiconductor power amplifier device such as a triode, an LDMOS, an IGBT, etc., and the present invention should not be understood by taking the N-type field effect transistor as a single example herein as a limitation to the scope of the present invention.

Wherein, NH1 is a pull-up driving tube for driving the upper half cycle of the output signal; NH2 is a small proportion mirror image of the pull-up driving tube and is used for detecting the output current of the pull-up driving tube; NL1 is a pull-down drive tube for driving the lower half cycle of the output signal; NL2 and NL3 are small-scale mirrors of the pull-down drive transistor for comparison to a reference in the pull-down drive current control loop; the operational amplifiers OP1, OP2 and OP3 are respectively used for loop control; the input resistor Rin and the feedback resistor Rf are used for adjusting the voltage gain of the power amplifying circuit; the current selector outputs the selected control current to the current control loop.

In this embodiment, the single-end driven push-pull power amplifying circuit is composed of a voltage amplifying circuit, a current detecting circuit, a current selector and a current control loop. The voltage amplifying circuit is connected with the current detecting circuit, the current detecting circuit is connected with the current selector, and the current selector sends the selected current to the current control loop to control the current of the output tube.

In a more specific embodiment, the voltage amplifying circuit may adopt an enhanced emitter-follower amplifying circuit, which is formed by an operational amplifier OP1, an output power tube NH1, a feedback resistor Rf, and an input resistor Rin, and has a voltage gain of-Rf/Rin, in combination with fig. 1. The operational amplifier OP1 and the feedback resistance networks Rf and Rin form an inverting input operational amplifier circuit. In applications with different requirements on voltage gain, the operational amplifier OP1 and the feedback resistor networks Rf and Rin may be replaced by other types of amplifying/buffering circuits, such as a unity gain buffer amplifier, a non-inverting input operational amplifier circuit, etc. It is even possible to omit the amplifier circuit, and the input terminal is directly connected to the gate control of NH1 and NH2, so that both NH1 and NH2 operate in emitter-follower amplification mode, i.e. as voltage amplifier circuits of unit gain buffer, respectively, and an emitter-follower amplifier circuit structure is formed.

NH2 is a small-scale mirror power tube of NH1, and NH2 is generally one ten-thousandth to one tenth of NH 1. The operational amplifier OP2, NH2 and the transistor PH1 together form a current detection circuit. The output voltage of the operational amplifier OP2 is the same as the positive input voltage, i.e., the voltage at the OUT pin. This results in the same gate, source, and drain voltages at NH2 and NH1, so the NH2 current is scaled down exactly to the NH1 current. This current passes through PH1 and into a current selector for a pull-down driven current control loop.

The current detection circuit composed of OP2, PH1 and NH2 may also be implemented in various ways. Different specific implementations do not affect the coverage of this embodiment.

Pins I1 and I2 of the current selector respectively receive two paths of current input, and output a path of smaller current, namely lmin, to the current control loop through comparison and selection. A larger path of current, namely lomx, is output through an lmax pin and can be used for auxiliary functions such as overcurrent alarm monitoring and the like.

The current selector selects a smaller current from the output currents of the Iref1 and the current detector passing through the PH1, and the current selector and the Iref2 are sent to a current control loop together for controlling the current of the output tube.

The operational amplifier OP3, the output power tube NL1, the small-proportion output mirror image power tubes NL2 and NL3, the current at the output end of the current selector Imin and the Iref2 jointly form a current control loop of the output tube.

When the output is positive half cycle, the voltage on the OUT pin is greater than the common mode value, and the direction of the output current is output from the pin. At this time, the pull-up driving tube NH1 is in working state, the pull-up output current detected by NH2 is greater than the Iref1 reference current, and the current comparator output is the value of Iref 1. The current control loop maintains the current at NL1 at a quiescent bias point determined by Iref1 and Iref2, where the Iref1 current is approximately equal to the Iref2 current.

When the output is negative half cycle, the voltage on the OUT pin is smaller than the common mode value at the moment, and the direction of the output current is input from the pin. At this time, the pull-down drive pipe NL1 is in a driving operation state. At this time, the voltage loop formed by the OP1, the NH1 and the feedback network still works, the voltage feedback control loop enables the output voltage to meet the requirement, the working current of NH1 is the working current set by the Iref2, and it should be noted here that, in this embodiment, the Iref2 may be used as a static working current as a reference current, of course, the reference current may also be dynamic, or a reference working current obtained by synthesizing a plurality of currents is used, and the function of the reference working current can be applied in an appropriate manner of controlling and limiting the corresponding power tube working current such as NH 1. If the output voltage at the OUT pin, NL1, pull-down driving current is too large, then extra current flowing through NL1 will be provided through NH1, so that the current in NH1 will be larger than the set working current, for example, it can be a set static working current, the current detection circuit outputs NH2 proportional current larger than Iref2, the minimum current output by the current selector is also larger than Iref2, the output voltage of OP3 amplifier becomes low, and NL1 gate voltage is reduced, so that the pull-down driving current is reduced, thereby forming a complete current control negative feedback loop. Similarly, if the NL1 pull-down driving current is too small at the output voltage of the OUT pin, the current in NH1 will be smaller than the set working current, and when the current detection circuit outputs NH2 proportional current smaller than Iref2, the minimum current output by the current selector is smaller than Iref2, the output voltage of the OP3 amplifier becomes high, and the NL1 gate voltage is increased, so that the pull-down driving current is increased, thereby forming a complete current control negative feedback loop.

In the above embodiment, the current control loop and the voltage control loop work together to perform feedback control on the output voltage and the output current, respectively. Therefore, the overall performance of the circuit is improved to the maximum extent on the premise of normal operation.

It should be noted that in a specific embodiment, since the load characteristics of different power driving transistors are different, an additional frequency compensation path may need to be added on the basis of the above circuit. For example, a filter capacitor is connected in parallel across the feedback resistor Rf. The frequency compensation path does not affect the critical signal control loop and the overall circuit driving method.

In a specific application embodiment, the power driving amplifying circuit can be integrated in a circuit chip. In order to facilitate the application of the power-driven amplifier circuit in specific products, the single-ended power-driven amplifier circuit may be integrated into a circuit chip for use, for example, in an application scenario such as audio amplification driving. Of course, the solution of the present embodiment may also be implemented by using conventional circuit module components according to specific use requirements or design requirements, and integrated packages, or packages divided into blocks according to circuit module differentiation, or the like, or be used in combination with other circuit modules as appropriate.

In yet another specific embodiment, fig. 4 shows a method for implementing class b/class ab power driving, which may be implemented by the single-ended driving push-pull power amplifying circuit shown in fig. 1 according to this embodiment.

In this method, the power amplifier tubes of the pull-up drive and the pull-down drive have the same dominant carrier type. The specific type of the semiconductor power device can be any one of semiconductor power amplifying tubes such as an N-type field effect tube, an NPN triode, a P-type field effect tube, a PNP triode and the like.

The pull-up driving power tube of the push-pull output is controlled by a voltage feedback control loop, so that the output voltage of the circuit meets the working requirement. In the specific embodiment, the operation amplifier can be used to form an active feedback network, and can also be realized by utilizing the characteristics of the device, for example, when an N-type field effect transistor is used for working, the operation is realized by setting the N-type field effect transistor in an emitter following amplification mode.

The other path of the push-pull amplification output is controlled by a set of current feedback control loop. For example, the pull-down drive tube is controlled by a proportional control method of current. The proportional control of the current, the use of operational amplifiers, or the implementation of current mirror circuits, etc., may be used.

In the method, the output current of the pull-up driving tube is detected by using a pull-up current detection module. The specific implementation mode is as follows: the current output by the pull-up current detection module and a working current reference value (the current reference value may be, for example, a static working current) are sent to a current comparison selector together, and then current comparison and selection are performed to select the smaller or larger of the two input currents. And the current selected by the current comparison selector is used for the current feedback control module.

Even though the current comparison selector may have different implementations, the input/output interface and the specific implementation function are consistent with those of the embodiments, and all that is included in the coverage of the method.

In the specific implementation of the scheme, the working principle of the circuit is the same as that of the circuit: voltage feedback control is applied to the pull-down driving tube, and current feedback control is applied to the pull-up driving tube. Under the condition, the current comparison selector detects the current of the pull-down driving tube, and the current is compared with the working current by the current comparator and output.

Example 2

Based on the single-end driven push-pull power amplifier circuit in embodiment 1, a corresponding differential driven push-pull power amplifier circuit may also be designed for application. In the embodiment, as shown in fig. 2, the power transistor is illustrated by using an N-type field effect transistor as an example, but of course, the power transistor herein may be a field effect transistor, and may also be any semiconductor power amplifier device such as a triode, an LDMOS, an IGBT, etc., and the present invention should not be understood by taking a single N-type field effect transistor as a limitation to the scope of the present invention.

Wherein, NH1/NH4 is a pull-up driving tube used for driving the upper half cycle of the output OUTP/OUTN signal; NH2/NH5 and NH3/NH6 are small-scale images of the pull-up driving tube and are used for detecting the output current of the pull-up driving tube; NL1/NL4 is a pull-down drive tube for driving the lower half cycle of the output signal; NL2/NL5, NH3/NH6 are small scale mirrors of the pull-down drive tube for reference comparison in the pull-down drive current control loop; the operational amplifiers OP1P/OP1N, OP2P/OP2N, OP3P/OP3N are respectively used for loop control; the input resistor Rinp/Rinn and the feedback resistor Rfp/Rfn are used for adjusting the voltage gain of the power amplifying circuit; the current selector outputs the selected control current for the current control loop.

The operational amplifier OP1P/OP1N, the output power tube NH1/NH4, the feedback resistor Rfp/Rfn and the input resistor Rinp/Rinn jointly form an enhanced emitter follower amplifier circuit which respectively drives an OUTP pin and an OUTN pin of differential output, and the differential output voltage gain of the amplifier circuit is (Rfp + Rfn + Rinp + Rinn)/(Rinp + Rinn). The operational amplifier OP1P/OP1N and the feedback resistance network Rfp/Rfn, Rinp/Rinn form a single-end differential conversion amplifying circuit together. In an application environment with different requirements on voltage gain, the enhancement type emitter amplifying circuit formed by the operational amplifier OP1P/OP1N and the feedback resistance network Rfp/Rfn, Rinp/Rinn together can be replaced by other types of amplifying/buffering circuits, such as a unit gain buffer amplifier, an inverse or in-phase differential operational amplifying circuit, and the like. In some application environments, the input terminals of the removable operational amplifiers OP1P/OP1N are directly connected to the gate control terminals of NH1/NH2/NH3, NH4/NH5/NH6, respectively, and at this time, NH1/NH4, NH2/NH5, and NH3/NH6 all operate in the emitter follower amplification mode, i.e., they are voltage amplification circuits that are used as unit gain buffers, respectively.

NH2/NH5 and NH3/NH6 are respectively small-proportion mirror power tubes of NH1/NH4, and generally, the sizes of NH2/NH4 and NH3/NH6 are respectively ten thousandth to one tenth of that of NH1/NH 4. The operational amplifiers OP2P/OP2N, NH2/NH4, PH1/PH3 and PH2/PH4 respectively form a differential positive terminal and a differential negative terminal current detector. The output voltages of the operational amplifiers OP2P/OP2N are the same as the voltage at the OUTP/OUTN pins, respectively. Thus, the gate, source and drain voltages of NH1/NH2/NH3 are all the same, so the NH2/NH3 current and the NH1 current are scaled down precisely. After this current passes through PH1/PH2, the output currents Iph1/Iph2 will be used in the current control loop for the differential positive side pull-down drive. Similarly, the gate, source, and drain voltages of NH4/NH5/NH6 are the same, so the current of NH5/NH6 is scaled down with the current of NH 4. After the current passes through PH3/PH4, the output current Inh1/Inh2 is used for a current control loop of the differential negative terminal pull-down driving.

In the above embodiments, the current detection circuit formed by OP2P, PH1 and NH2 and the current detection circuit formed by OP2N, PH3 and NH5 may be implemented in different ways. Even the current detection circuit can have various specific implementations, and the specific implementation functions are consistent with the embodiments and are within the coverage range of the method.

Pins I1 and I2 of the current selector respectively receive two paths of current inputs of an Iph1 and an Inh1, and a path of smaller current Imin and a path of larger current Imax are obtained through comparison and selection. The larger current Imax output by the Imax pin can be used for generating auxiliary functions such as dynamic bias or overcurrent alarm monitoring and the like. And the smaller current Imin output by the current selector is used for controlling the common-mode current of the pull-down driving tube.

The operational amplifier OP3P/OP3N, the output power tube NL1/NL3 and the corresponding small-proportion output mirror image power tube NL2/NL4 together form a current control loop of the output tube. The input of the current control loop is Ipl/Inl, which is obtained by subtracting the output current Imin of the current selector and then adding the reference current Iref by using the detection currents Inh2/Iph2 on the opposite sides of the difference. I.e. Ipl-Inh 2-Imin + Iref and Inl-Iph 2-Imin + Iref. In another embodiment, in the current control loop, the differential opposite-side detection currents Inh2/Iph2 may be used as the input Ipl/Inl, the output current Imin of the current selector is subtracted, or a weight k is set for the subtracted output current Imin of the current selector, taking Ip1 as an example, that is, the specific calculation method may be Inh2-Imin, or Inh 2-iminxk, and the solution of Inl is similar thereto, and will not be described again. In yet another specific embodiment, in the current control loop, the differential opposite side detection current Inh2/Iph2 may be used as the input Ipl/Inl, to subtract a proportion of the output current Imin or Imin of the current selector, and add a dynamic reference current after adding the reference current Iref, taking Ip1 as an example, that is, the specific calculation method may be Inh2-Imin + Iref + Id, or Inh 2-iminxk + Iref + Id, and the solution of Inl is similar to that, and will not be described again. The addition and subtraction of the current can be easily performed in the circuit by using a current mirror or an operational amplifier, and are not described herein again.

In normal operation, the operational amplifier OP3P controls the gate voltages of NL1 and NL2 such that the voltage at the input of the operational amplifier, the voltage at the OUTP, and the voltage at the drain of NL2 are substantially equal. NL1 and NL2 have the same gate, source and drain voltages, and thus have the same operating current ratio as NL2 to NL 1. The current controlling the output pull-down drive tube NL1 is thus identical to the input control current Ipl. For example, if the pull-down driving current, i.e. the current of the input OUTP is larger than the target current, the voltage of the OUTP is lower due to the output impedance of NL1, the output voltage of the operational amplifier OP3P is decreased, and the currents through the gate controls NL1 and NL2 are decreased, so that the output pull-down driving current is consistent with the target current, and a complete current negative feedback path is formed.

Similarly, OP3N, NL3 and NL4 form a current control negative feedback loop for the differential negative terminal, controlling the current stabilizing output of the differential negative terminal.

Different from single-ended driving, in differential driving, in addition to ensuring differential output voltage and differential output current, that is, the difference between the output voltage and the output current of the OUTP and the OUTN meets the use requirement, a common mode feedback control loop is also needed, so that the output common mode voltage of the OUTP and the OUTN and the common mode working current of the power output stage are stable.

In this embodiment, the common mode voltage of the differential output is stably controlled by a voltage feedback control loop. OP1P/OP1N, Rinp/Rinn and Rfp/Rfn form a single-end to differential voltage amplifying circuit. The common mode value of the INPUT is determined by the INPUT pin AC _ GND voltage connected to the positive INPUT of OP1N and the INPUT voltage of the INPUT pin INPUT. In the embodiment, the dc voltage of the input pin is also set to AC _ GND voltage, and the signal is input through AC coupling, so the output common mode voltage of the embodiment is determined by AC _ GND. And is stabilized by negative feedback control of the operational amplifier OP1P/OP 1N.

The common mode current of the power output stage, i.e. the current flowing through both the pull-up drive transistor and the pull-down drive transistor, is for example the current through both NH1 and NL1, or both NH4 and NL 3. In this embodiment, the output minimum current of the current selector is the common mode working current; in a specific embodiment, in the input of the output current control loop, the common mode current is subtracted from the input control current, and a reference current Iref is added, so that the common mode operating current of the power output stage can be set to a bias point determined by Iref, thereby performing stable operation.

The specific working principle of this embodiment is that, when the output of the differential positive side output pin OUTP is a positive half cycle, the voltage on the OUTP pin is greater than the output common mode value, and the output current direction is output from the pin. At this time, the pull-up driving tube NH1 is in operation, and the pull-up output current Iph2 of NH1 is detected by NH2 and sent to the pull-down current control loop output by the differential negative terminal. At the same time, the current control loop for the positive differential side will maintain the current at NL1 at a static bias point, which is determined by Iref as follows:

when the output of the differential positive-side output pin OUTP is a positive half cycle, the output of the differential negative-side output pin OUTN is a signal negative half cycle, and the direction of the output current is input from the pin. At this time, the pull-down driving transistor NL3 is in a power output state, and its output current Inl is Iph2-Imin + Iref, which is basically determined by Iph2, i.e., the same as NH 1. The pull-up driving pipe is in a static working state. At this time, the current of NH4 is small and is a quiescent current, so that the current values Inh1/Inh2 detected in the current detection circuit are small.

In the working half-cycle, the input current Iph1 of the current selector is much larger than Inh1/Inh2, so the Imin current is equal to Inh1/Inh 2. The operating current for NL2 is therefore Inh2-Inh1+ Iref, in general in this embodiment Inh1 is Inh2, so the operating current for NL2 is Iref.

As described above, when the output of the differential positive side output pin OUTP is positive half cycle, the voltage feedback circuit controls the voltage output of OUTP and OUTN, and the current control circuit ensures that the currents of the pull-up driving transistor NH1 and the pull-down driving transistor NL3 are the same in magnitude and opposite in direction. At this time, the pull-up driving transistor NH4 and the pull-down driving transistor NL1 operate at a static bias point, and the current thereof is determined by Iref.

Similarly, when the differential positive side output pin OUTP has a negative half cycle, NL1 and NH4 are in a power-driven operating state, while NH1 and NL3 are in a static operating state.

In the overall view, when the differential output is driven, the current control circuit and the voltage control circuit act together respectively in different working periods to perform feedback control on the output voltage and the output current respectively, so that the whole power amplifier works normally.

It should be noted that in a specific embodiment, since the load characteristics of different power driving transistors are different, an additional frequency compensation path may need to be added on the basis of the above circuit. For example, a filter capacitor is connected in parallel across feedback resistor Rfp/Rfn. The frequency compensation path does not affect the critical signal control loop and the overall circuit driving method.

In addition, a current feedback control loop composed of the operational amplifier OP3P/OP3N, the pull-down driving tube NL1/NL3, the pull-down small-proportion current mirror tube NL2/NL4 and the like can also have different current proportion feedback modes. And in different specific implementation scenarios, different frequency compensation networks are required. Different current proportional feedback modes are possible in different current feedback control loops. I.e., different frequency compensation networks that may be needed in different specific implementation scenarios. All such variations are within the scope of the method as long as they do not affect the core method and circuit implementation of the embodiment.

In an embodiment, the power-driven amplifier circuit may be integrated in a circuit chip. In order to facilitate the application of the power-driven amplifier circuit in specific products, the differential power-driven amplifier circuit may be integrated into a circuit chip for use, for example, in an application scenario such as audio amplification driving. Of course, the solution of the present embodiment may also be implemented by using conventional circuit module components according to specific use requirements or design requirements, and integrated packages, or packages divided into blocks according to circuit module differentiation, or the like, or be used in combination with other circuit modules as appropriate.

In yet another specific embodiment, fig. 5 shows a method for implementing a differential output class b/class ab power driving, which can be implemented by the differential driving push-pull power amplifying circuit shown in fig. 2 according to this embodiment.

In this method, the power amplifier tubes of the pull-up drive and the pull-down drive have the same main carrier type. The specific type of the semiconductor power device can be any one of semiconductor power amplifying tubes such as an N-type field effect tube, an NPN triode, a P-type field effect tube, a PNP triode and the like.

The pull-up driving power tube of the push-pull output is controlled by a voltage feedback control loop, so that the output voltage of the circuit meets the requirement. The feedback control loop can be realized by an active feedback network, for example, using an operational amplifier, or by using the characteristics of the device itself, for example, using an N-type field effect transistor to operate, and setting the feedback control loop in an emitter-follower amplification mode.

The other path of the push-pull amplification output is controlled by a set of current feedback control loop. For example, the pull-down drive tube is controlled by a proportional control method of current. This can be realized by using an operational amplifier, a current mirror circuit, or the like. The specific different implementation manners are all within the coverage of the embodiment.

In the method, the output current of the pull-up driving tube is detected by using a pull-up current detection module. And the current comparison selector is sent to a current comparison selector together with a working current reference value (the working current reference value can be, for example, a static working current reference value), current comparison and selection are carried out, and the smaller or larger one of the two paths of input currents is selected. And the current selected by the current comparison selector is used for the current feedback control module. It should be noted that, in this embodiment, the operating current reference value may be a static operating current as a reference current, and of course, the reference current may also be dynamic, or a reference operating current obtained by using a plurality of currents in combination may be used, and the function of the reference operating current can be implemented in an appropriate manner for controlling and limiting the corresponding operating current of the power tube.

The current comparison selector may have different implementations, but if the input/output interface and the specific implementation function are consistent with those of the embodiment, the specific different implementations also fall within the coverage of the method.

In a specific implementation of the scheme, voltage feedback control may be applied to the pull-down driving tube, and current feedback control may be applied to the pull-up driving tube. In such a case, the current of the pull-down driving tube will be detected and compared with the operating current by the current comparator and outputted.

Example 3

In another specific embodiment, in conjunction with fig. 3, the present invention further provides a circuit design method of a preferred current selector.

In the current selector module, I1 and I2 are two input current signals of the module, and Imin and Imax are two output current signals of the module. The current comparator CMP obtains comparison results outp and outn by sampling and comparing the input current. When the current of the input positive terminal is large, the outp output is high level, and the outn output is low level; when the current to the positive input terminal is small, the outp output is low and the outn output is high. The PSW1/PSW2/PSW3/PSW4 are four P-type field effect transistors respectively and are used for carrying out switch selection on input current signals.

The working principle of the current comparison selection of the circuit module is as follows: when the I1 current is large, the input positive terminal signal of the current comparator is high, outp outputs high level, and outn outputs low level. At this time, the SW1 is turned off, the PSW2 is turned on, and the I1 signal is selected to be output to the Imax pin; while PSW3 is on, PSW4 is off, and I2 current is selected to the Imin pin. Similarly, when the current of I2 is larger, I2 is sent to Imax pin, and I1 is sent to Imin pin. Therefore, the maximum and minimum selection functions of the input current are realized, namely, a smaller current signal in the input pin is sent to the Imin pin, and a larger current signal is sent to the Imax pin.

In yet another embodiment, the present solution may be implemented by means of cooperation of circuit modules of each part, and each circuit module may include a corresponding module for performing each or several steps in each of the above embodiments. Thus, each step or several steps of the above described embodiments may be performed by a respective module, and the circuit module may comprise one or more of these functional modules. The circuit modules may be one or more active or passive electronic devices specifically configured to perform the corresponding functions, or may be implemented by integrated circuits configured to perform the corresponding functions, or some of the functional modules may be implemented by analog/digital conversion, by an external processor such as a signal processor, a microcomputer, or some combination thereof.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing circuit blocks which include one or more steps for performing the recited signal operation and control, and alternate implementations are included within the scope of the preferred embodiment of the present disclosure in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of implementation of the present disclosure.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A power driving amplifying circuit is characterized in that the circuit is in single-end driving;

the power driving amplification circuit comprises a voltage amplification circuit, a current detection circuit, a current selector and a current control loop; the voltage amplifying circuit is an emitter following amplifying circuit, the emitter following amplifying circuit is connected with a current detecting circuit, the current detecting circuit is connected with a current selector, and the current selector sends the selected current to a current control loop for controlling the output current;

the voltage amplifying circuit consists of an inverse input operational amplifying circuit and a power tube NH1 connected with the output end of the inverse input operational amplifying circuit;

2. The power-driven amplifier circuit according to claim 1, wherein the power transistor NH1 is a pull-up driving transistor, and the power transistor NL1 is a pull-down driving transistor;

3. The power-driven amplifier circuit according to claim 1, wherein the inverting input operational amplifier circuit is composed of an operational amplifier OP1, a feedback resistor Rf, and an input resistor Rin;

the output end of the operational amplifier OP1 is connected with the gate of the power tube NH 2.

4. The power-driven amplifier circuit as claimed in claim 1, wherein the non-inverting input terminal of the operational amplifier OP2 is connected to the source of a power transistor NH1 and the output pin of the power-driven amplifier circuit;

5. The power-driven amplification circuit of claim 1, wherein the inverting input terminal of the operational amplifier OP3 is connected to the output current terminal Imin selected by the current selector and the drain of the power tube NL 2; the non-inverting input end of the operational amplifier OP3 is connected with a working current Iref 2;

6. A method of power-driven amplification for use in class b or class ab power-driven amplification, the method comprising:

applying voltage feedback control to the pull-up driving power tube and applying current feedback control to the pull-down driving power tube; controlling the pull-up driving power tube connected with one path of the push-pull output by a voltage feedback control loop to enable the output voltage of the circuit to meet the preset working requirement; controlling the pull-down driving power tube connected with the other push-pull output path by a current feedback control loop; detecting the pull-up current, comparing the pull-up current with a working current reference value, selecting a larger or smaller current, and inputting the larger or smaller current into a current feedback control loop to realize current feedback control on the pull-down driving power tube; or,

applying voltage feedback control to the pull-down driving power tube and applying current feedback control to the pull-up driving power tube; controlling the pull-down driving power tube connected with one push-pull output path by a voltage feedback control loop so that the output voltage of the circuit meets the preset working requirement; controlling the pull-up driving power tube connected with the other path of the push-pull output by a current feedback control loop; detecting the pull-down current, comparing the pull-down current with a working current reference value, selecting a larger or smaller current, and inputting the larger or smaller current into a current feedback control loop to realize current feedback control of the pull-up driving power tube;

7. A power driving amplifying circuit is characterized in that the power driving amplifying circuit is in differential driving;

the first emitter follower amplification circuit is used for driving an OUTP (output terminal) pin of differential output, and the second emitter follower amplification circuit is used for driving an OUTN (output terminal) pin of differential output;

8. The power-driven amplification circuit of claim 7, wherein the first current control loop is formed by operational amplifiers OP3P, NL1, NL 2;

the second current control loop consists of operational amplifiers OP3N, NL3 and NL 4;

9. A power driving amplification method is applied to B type or AB type differential output push-pull amplification output driving, and comprises the following steps:

applying voltage feedback control based on an active feedback network to a pull-up driving power tube connected with a push-pull output, so that the output voltage meets the voltage requirement; applying current feedback control to a pull-down driving power tube connected with the other path of the push-pull output; detecting a pull-up current, comparing the pull-up current with a working current reference value, selecting a larger or smaller current, and taking the selected output current of the circuit, the working current and the current detection circuit as a control basis of current feedback control on a pull-down driving power tube; or alternatively

10. The power-driven amplification circuit of one of claims 1 and 7, wherein the current selector comprises: a current comparator CMP, field effect transistors PSW1, PSW2, PSW3, PSW 4;

11. The power-driven amplification circuit of one of claims 1 and 7, wherein the power-driven amplification circuit is integrated in a circuit chip; or,

the power driving amplifying circuit is packaged in a blocking mode based on the circuit module.

12. The power-driven amplification circuit of one of claims 1 and 7, wherein the power-driven amplification circuit is applied to audio power amplification.

13. The power-driven amplification circuit of any one of claims 1 and 7, wherein the power transistor is any one of a field effect transistor, a triode, an LDMOS and an IGBT.

14. The power-driven amplification method according to any one of claims 6 and 9, wherein the power transistor is any one of a field effect transistor, a triode, an LDMOS and an IGBT.